Adding a pre amp

[barrows]

1 hour ago, Kimo said:

Did you leave because he wanted you to design a preamp?

Hahaha!  I am not an engineer nor an audio circuit designer.  I worked for PS Audio in the sales department as head of Customer Service and technical support.  Basically talking to customers and dealers all day, helping them with system set up, advice, selling gear, setting up show demo systems, and handling repairs and such.

[barrows]

1 hour ago, diecaster said:

 

 

How is it different? I quoted people or provided videos of their own words. In this case, barrow's "story" is that what Paul McGowan says is not true and he is driven purely by greed. He is correlating that since PS Audio came out with a tube preamp, his story has changed on how preamps sound. He is suggesting it's not because the preamp actually sounds better to Paul. The causation is much more likely to be that the preamp sounds better to Paul and that is why Paul had BHK design a preamp for PS Audio.

Please do not put words into my mouth, I said none of the above.

But I do know why PS Audio added a preamp to their lineup, their dealers demanded a matching preamp to pair with the BHK amplifier.

Let's, perhaps move this conversation away from PS Audio, and talk more generally, as I have no desire to throw any audio company under the bus.  i have great deal of respect for Paul, and what he has done at PS Audio, they make some great gear, and Paul really does care about offering high value products.

[barrows]

34 minutes ago, Kimo said:

 Huh?  How do add depth, other than by revealing more information?  How do you know what the proper dynamics are?  Fullness, maybe.

It is impossible to reveal more information by adding an extra component to the playback chain.  Adding a preamp cannot increase actual resolution.  This is not an opinion it is a fact.

[mansr]

25 minutes ago, Ralf11 said:

BTW - don't some pre-amps use digital vol. controls?

Digitally controlled analogue attenuators are common. Is that what you meant?

[Kimo]

Just now, barrows said:

It is impossible to reveal more information by adding an extra component to the playback chain.  Adding a preamp cannot increase actual resolution.  This is not an opinion it is a fact.

No, it is opinion.  Much is spewed about here as absolute, and of course all of it is just opinion.

 

I will give you this.  Provided the volume control and output stage of the DAC are of the same quality, or better than the preamp, and the DAC is capable of driving the amp correctly, there should be no reason to add a preamp.  Anything else, and you need to measure/listen.  

[pkane2001]

2 minutes ago, Kimo said:

No, it is opinion.  Much is spewed about here as absolute, and of course all of it is just opinion.

 

I will give you this.  Provided the volume control and output stage of the DAC are of the same quality, or better than the preamp, and the DAC is capable of driving the amp correctly, there should be no reason to add a preamp.  Anything else, and you need to measure/listen.  

 

Reminds me of the sampling rate thread. There are things we know without having to prove them empirically— mathematics and logic are like that.

 

There is nothing you can do to the signal to increase resolution if it’s not already present in the input signal. You can change the signal, interpolate, distort it, add to it other signals, but you can’t reproduce real details that are not already present. 

 

The only proper way way to do this is called deconvolution. It’s a mathematical way to undo distortions. I suggest that very, very few if any preamps do true deconvolution. It’s a really hard, if not impossible, thing to do well. Especially automatically. Now that would be a great product if someone could come up with it!

[Fitzcaraldo215]

33 minutes ago, mansr said:

Digitally controlled analogue attenuators are common. Is that what you meant?

Yes, but to avoid confusion, a digitally controlled attenuator for use in an analog circuit is still an analog device, albeit with digital controls.  It attenuates signal purely in the analog domain, and no a-d or d-a is necessary to use it.

 

OTOH, a digital volume control operates entirely in the digital domain by shifting the bits in each PCM signal word.

[Kimo]

14 minutes ago, pkane2001 said:

 

Reminds me of the sampling rate thread. There are things we know without having to prove them empirically— mathematics and logic are like that.

 

There is nothing you can do to the signal to increase resolution if it’s not already present in the input signal. You can change the signal, interpolate, distort it, add to it other signals, but you can’t reproduce real details that are not already present. 

 

The only proper way way to do this is called deconvolution. It’s a mathematical way to undo distortions. I suggest that very, very few if any preamps do true deconvolution. It’s a really hard, if not impossible, thing to do well. Especially automatically. Now that would be a great product if someone could come up with it!

It would be an even greater product if we could use it on politicians.  

[Ralf11]

39 minutes ago, mansr said:

Digitally controlled analogue attenuators are common. Is that what you meant?

 

dunno - some say they are; some act like digital - I have not pulled them apart to see

[mansr]

5 minutes ago, Fitzcaraldo215 said:

Yes, but to avoid confusion, a digitally controlled attenuator for use in an analog circuit is still an analog device, albeit with digital controls.  It attenuates signal purely in the analog domain, and no a-d or d-a is necessary to use it.

Right. A switched resistor network setting the gain of an opamp is one possible implementation.

 

5 minutes ago, Fitzcaraldo215 said:

OTOH, a digital volume control operates entirely in the digital domain by shifting the bits in each PCM signal word.

Bit shifting can only give you 6 dB steps. Finer control requires multiplication.

[mansr]

4 minutes ago, Ralf11 said:

dunno - some say they are; some act like digital - I have not pulled them apart to see

What do you mean by "act like digital"?

[diecaster]

58 minutes ago, barrows said:

Please do not put words into my mouth, I said none of the above.

But I do know why PS Audio added a preamp to their lineup, their dealers demanded a matching preamp to pair with the BHK amplifier.

Let's, perhaps move this conversation away from PS Audio, and talk more generally, as I have no desire to throw any audio company under the bus.  i have great deal of respect for Paul, and what he has done at PS Audio, they make some great gear, and Paul really does care about offering high value products.

 

No, you did not put those exact words down, but you can't deny that is exactly what you implied. If you had respect for Paul, you would not have implied what you did.

[fas42]

1 hour ago, esldude said:

The fullness and depth you speak of are an additive coloration.  Very pleasant, very nice on some music.  An effect added all the same.  The depth and fullness are not in the recorded signal it is being added. 

 

We've had this argument before, I know ... but you're wrong. Fullness and depth are the intrinsic characteristics of the recordings, always - and I know this because on the path of optimising a setup the sound goes from mediocre, "solid state" character, to "fullness and depth". Every time. If you are not getting full and deep playback, then it means that you are hearing too much distortion - not the other way round.

 

I've never used tubes once, in 30 years. Because the qualities that I'm looking for exist already on all the recordings; I just need to create a transparent path for retrieving what's there ...

[fas42]

4 minutes ago, fas42 said:

 

 

 

When are we going to get the ability to delete a post ...

[fas42]

57 minutes ago, mansr said:

Digitally controlled analogue attenuators are common. Is that what you meant?

 

The consumer grade Philips HT rig I played with for some years used a low grade, Japanese IC for this; but the quality here was still good enough to get me the results I was after - if it had been a classic analogue pot, I would have needed to spend a lot more time bypassing this weakness.

[barrows]

15 minutes ago, diecaster said:

 

No, you did not put those exact words down, but you can't deny that is exactly what you implied. If you had respect for Paul, you would not have implied what you did.

OK, I cannot control what you choose to believe.  But I would prefer it if when referring to me, that you listen to my actual words, and choose to talk about them, rather than your own interpretation of my words.  As I said, I have a great deal of respect for Paul.  That respect does not require that I agree with everything he says.

People can respect one another and still disagree, at least in my complex and rational world this is possible, apparently it is not in yours?

[diecaster]

12 minutes ago, barrows said:

OK, I cannot control what you choose to believe.  But I would prefer it if when referring to me, that you listen to my actual words, and choose to talk about them, rather than your own interpretation of my words.  As I said, I have a great deal of respect for Paul.  That respect does not require that I agree with everything he says.

People can respect one another and still disagree, at least in my complex and rational world this is possible, apparently it is not in yours?

 

You didn't use words....you told us draw our own conclusions. I did!

 

See here:

 

5 hours ago, barrows said:

Well, also, when PS Audio did not make a preamp they recommended DAC direct to amp.  When they started development of a preamp, suddenly the recommendation changed.  Draw whatever conclusion you will.

 

Gosh, I wonder what conclusion I supposed to draw here...my conclusion is that you are saying that PS Audio, and by extension Paul, will lie to make money.

[fas42]

A basic problem with DAC directly driving an amplifier is that the level of currents flowing into into the input load of the amp are of a high enough, varying with signal, level to disturb the electrical environment of the DAC - meaning, poorer sound. Of course, competent engineering should resolve all that ... and this always happens with consumer gear, .

 

A local audio friend has wrestled with this dilemma for ages - direct is best, but the quality steadily degrades as the volume is increased, because more current drive is needed; inserting a buffer stops the variation with volume, but then the SQ is degraded all the time, from the characteristics of the buffer.

[esldude]

2 minutes ago, fas42 said:

A basic problem with DAC directly driving an amplifier is that the level of currents flowing into into the input load of the amp are of a high enough, varying with signal, level to disturb the electrical environment of the DAC - meaning, poorer sound. Of course, competent engineering should resolve all that ... and this always happens with consumer gear, .

 

A local audio friend has wrestled with this dilemma for ages - direct is best, but the quality steadily degrades as the volume is increased, because more current drive is needed; inserting a buffer stops the variation with volume, but then the SQ is degraded all the time, from the characteristics of the buffer.

So no one buffers the output of their DAC/pre?  Are you serious?  How many ways can someone misunderstand that a DAC analog output stage has the same job as a pre-amp analog output stage?

[barrows]

3 minutes ago, fas42 said:

A local audio friend has wrestled with this dilemma for ages - direct is best, but the quality steadily degrades as the volume is increased, because more current drive is needed; inserting a buffer stops the variation with volume, but then the SQ is degraded all the time, from the characteristics of the buffer.

And this problem is no different if the driving component is a DAC or a preamp.  As long as the component is competently engineered to drive enough current, there is no problem.

Just as there are poorly engineered DACs which may not be able to drive enough current to some amplifiers, there are poorly engineered preamps with the same problem.

Although, in the real world of available audio components, these "problems" are the exception rather than the rule.  One has to work a bit hard to combine an amp and DAC (or preamp) which will actually exhibit this type of problem.

[mansr]

4 minutes ago, esldude said:

How many ways can someone misunderstand that a DAC analog output stage has the same job as a pre-amp analog output stage?

14 pages worth.

[Kimo]

3 minutes ago, esldude said:

So no one buffers the output of their DAC/pre?  Are you serious?  How many ways can someone misunderstand that a DAC analog output stage has the same job as a pre-amp analog output stage?

I am a pretty sure that this is well understood.  I am also pretty sure that the general argument would be that the quality of the buffer is different on a dedicated preamp.

 

My Gill Audio DAC included the the Gill Audio preamp board and bunch of expensive transformers.  That was DAC designed just like a preamp, but alas it had no volume control.

[esldude]

2 minutes ago, Kimo said:

I am a pretty sure that this is well understood.  I am also pretty sure that the general argument would be that the quality of the buffer is different on a dedicated preamp.

 

My Gill Audio DAC included the the Gill Audio preamp board and bunch of expensive transformers.  That was DAC designed just like a preamp, but alas it had no volume control.

So use a digital volume control in software.

[fas42]

28 minutes ago, esldude said:

So no one buffers the output of their DAC/pre?  Are you serious?  How many ways can someone misunderstand that a DAC analog output stage has the same job as a pre-amp analog output stage?

 

The buffer within the DAC enclosure is not an ideal circuit, and the PS feeding it is also not ideal. Real world circuit behaviours intrude, and the SQ is degraded - the headache is that this typically happens at the edge of audibility; some people hear it happening, others don't ... and so they fight ...

[Kimo]

14 minutes ago, esldude said:

So use a digital volume control in software.

The DAC is long gone.  Only did 24/96.

I ran it straight into an Art Audio Carissa, which had a built in volume control.  I wouldn't think of adding a preamp to that set up, but I did try one anyway.  It was pointless.

 

That being said, the Art Audio guy was more fond of running the Carissa with a preamp, so go figure.